Super Glue & Balance Springs

[Sam StonesParticipant @samstones42903]

When I introduced the thread about near empty tubes of super glue, and although it was a significant irritation at being ripped off, I was actually in the middle of some final experiments to make a usable balance spring for my skeleton clock.

In previous threads about balance springs, I searched and tested several ideas to try to find (with my limited equipment), a reliable method. As my own notes show, I had determined that a wire diameter of 0.2mm (0.008″) would replace the flat section as used in the original clock design. This has since proved to be fairly accurate since the clock is now beating with an accuracy of less than 1 sec/hour, and responds well to fine adjustments.

That said, I can briefly describe my approach to making my balance springs. The most significant problem I have had when winding the spring onto a 4.0mm diameter mandrel has been how to uncoil it successfully after winding. Once released, the usual result has been for the spring to fly open and to wrap itself into an unuseable mess. There have been some very useful comments posted, some of which pointed to additional twisting which takes place (unseen) during the winding process.

Michael Williams wrote :- The traditional method of making very small springs with limited equipment is to pass the feed wire through a hole in a piece of flat soft wood and arrange for the flat part of the wood to bear down on the coils that you have already made . Until such time as you deliberately remove the wood the coil remains tight and under total control . You cut off surplus feed wire with the wood still in place and then slowly lift it away . As an added bonus there is an element of screw-cutting going on in the wood and after a few turns; a neat set of grooves form which help to keep the winding pitch constant . Please be very careful when winding springs under power – it is a terribly dangerous process.

Perhaps it was the hidden twist and how I anchored both ends of the wire which were responsible.

To avoid weakening the mandrel I had drilled the 1mm anchor hole through the larger 1/4″ diameter section. What seemed to be happening was that the wire was skidding down the side of the step, thus introducing extra twist. This was rectified in my final attempts.

The free end was weighted and the wire was passed over a simple pulley. I took the trouble to stop the weight from spinning, expecting that any back and forth twisting would be transferred to the spring. Taking note of all the warnings, winding the wire onto the mandrel had always been done by hand with the main power switch turned off. This was very tedious and tiring for my old hands and fingers, since reaching the three-jaw was awkward. I had also chosen to wind the spring ACW so that I could see a little more of what was happening to the winding process.

It was at that point that I decided to wind the wire under power with the lowest lathe speed (267 rpm), and in reverse. The chuck was bolted so there was never any danger from it unscrewing. I also calculated that I had at least 15 seconds before I had wound all of the 1 metre length of guitar string onto the mandrel. I stood ready to switch off, and hey presto, a nicely wound spring. That was until I removed the wood which Michael had suggested.

Another tangled mess!

That was when I went off at a tangent, and began to explore the possibility of gluing the wire to the mandrel, and using a solvent to let the spring slowly uncoil. The traditional `glue’ in clock making is shellac which dissolves in methylated sprits. This would be ideal, or so I thought. So I tried again giving the tightly wound wire a good coating of shellac, waiting overnight for it to set.

It didn’t work so I figured that the shellac had not found its way under the wire and onto the mandrel. With that fixed, I tried again. The wire instantly flew into another mess, and another guitar string went into the bin. I interpreted this result to mean that the shellac was too brittle, and/or hadn’t bonded sufficiently. It was also possible that the meths had not fully evaporated completely from under the coils.

That’s where the super glue came into the picture. I should (again) point out that super glue (cyanoacrylate) sets by combining with moisture from the atmosphere or from your breath. It is also supposed to soften in acetone, which would be ideal, or so I thought. With a very thin coating of super glue applied to the surface of the mandrel, I tried once more, applying two coats to the tightly wound coils. Several hours later, I cut the wire.

Whoops!

The wire uncoiled but didn’t tangle. But the freed wire was stuck together over much of the length of the spring, albeit at about the correct spring diameter of 9mm. I had my bottle of acetone (nail-polish remover) ready, and promptly dropped the spring into it. Nothing seemed to be happening. The coils remained stuck together, and the acetone seemed to be doing nothing either.

When I fished the spring from the acetone, it became clear that although the glue had turned white(ish) it was still present. Very carefully, I teased the coils free, and found that I had to strip off whiskery lengths of glue still attached to the wire.

Remember, the diameter of the wire is only 0.008″.

This posting may provide food for thought, but it has become more of a saga, so I must end here.

One question. Why didn’t the glue dissolve in the nail-polish remover?

[Sam StonesParticipant @samstones42903]

I wanted a reliable means of controlling the wire.

[Clive HartlandParticipant @clivehartland94829]

Because the nail polish remover is not pure, it has oils added to stop the spirit damaging the cuticles.

Unfortunately its hard to get Acetone in small quantities.

Perhaps buy the specialised super glue solvent!

 

Clive

[Sam StonesParticipant @samstones42903]

Thanks Clive,

 

That’s a super (glue) solution.

 

Since my clock is now working, I’m no longer in need of making more balance springs. I actually came close to emptying the music shop of their stock of their thinnest guitar strings.

 

However, I feel sure that your comments will serve to provide a neat answer should anyone care to develop this spring-making idea still further.

 

Thanks for your help.

 

Regards,

 

Sam

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again ,

 

 

Some super glues contain things such as setting time inhibitors and thickening agents – the glue itself will dissolve but not these additional components .

 

 

All your problems arise from putting secondary twists and varying bending forces into the wire when coiling . The only way to guarantee success with such a tiny spring is to either :

 

 

(1) Work with hardened wire and contrive a winding system where every action is controlled and repeatable so that even when it goes wrong you can make it go wrong the same way every time and learn and adapt . This really means making a set up where the wire is controlled by mechanical means at all times during winding – you don’t handle it at all .

 

 

(2) Work with softened wire and solve the rehardening and clean up problems . Probably not as difficult as it seems at first sight – Traditional method of hardening is to put spring onto a plain or threaded bar , cover spring with mixture of lime and soap and then harden and temper the whole lot using an exposed bit of the bar to judge temperature . The soap/lime mixture will dissolve away slowly in water leaving the spring clean and with a pleasing metallic grey type of finish . A variation on this method is to put the spring covered in a small open topped tray of fine sand and use a slip of plain steel as an indicator .

 

 

Personally I would put all my efforts into the hardened wire process .

 

MW

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again again ,

 

 

Since our much earlier discussion on this topic I’ve given thought from time to time as to what is actually happening inside the wire at the point of bending . I understand what is happening more completely now and just after completing my most recent posting the penny finally dropped as to how to control the bending action so as to be far more stable and predictable . Basically you are ‘doing too much in one go’ in trying to wind such a tight radius spring from straight wire . The answer to making these springs lies in the preconditioning of the (hard) wire before winding . You will have to work this out in detail by trial and error but essentially the spring has to be wound in at least two or possibly even several stages .

 

This will be something like :

 

(1) Curve the cut length of wire into a flat large radius circle .

 

(2) Curve the wire into successively tighter radius flat circles .

 

(3) Then either use the tightly curved wire to wind spring by normal means OR

 

(4) Wind a spring bigger in diameter and pitch than the one needed finally then rewind it

 

down to finished size .

 

A lot of work but this process will give good results .

 

MW

[Richard ParsonsParticipant @richardparsons61721]

Hi Sam,
When clock/watch makers talk of shellac it is not the same tackle that French Polishers use. A clock/watch maker buys the stuff as a stick (like sealing wax) which he heats up to melt it and use hot. These days I use a hot glue gun.

Spring making is quite an art/skill. If you are into clocks get yourself a copy of “Watch & Clock makers’ Handbook Dictionary and Guide by Britten. ISBN 1 85149 192 9.

Britten tells you to get spring wire in its soft form, Wind your spring, (there are a good few pages in Britten on doing that) then you harden your spring Britten also has a long description of this.

If you are getting ‘spring wire’ in its soft state the supplier will tell you about both the hardening and tempering temperatures.

Finally Sam There are composite carbon fibre springs

Rgds

Dick

[TSHParticipant @tsh73987]

For small quantities of acetone you might like to try

http://www.svsp.co.uk/Shop%20Website/pages/composite_repair_materials.htm

(usual disclaimer, just a satisfied customer).

 

Regards,

 

Trevor

[PatParticipant @pat]

Hi Sam

 

I have a rather vague recollection of hair springs being made for electric moving coil meters where the problem was to get uniform angular torsion over 270 degrees from five or six turns. The springs were phosphor bronze or it may have been beryllium copper and came in packets as straight lengths. The strips were rectangular in cross section and similar in section to the springs in pocket watches. A few pocket watch springs were used but found to be wanting in linearity.

 

The springs were formed by from the straight wire by gently pulling it between three dowels set into a block. The geometry of the dowels could be varied as each pin was set into a shallow wedge and each wedge clamped to a base and to each other. Pulling the strip through the dowels produced a nice uniform spring bend . The lead out and lead in were left straight and formed later using parallel action round nosed pliers. The pliers may have been specials or might been watch making tools. Conical springs resulted by inclining the pins such that the wire was forced against the support by the direction of pull. I don’t remember if the pins were inclined as well as the direction of feed angle. I do recall much time being spent on getting the form for the last and first turns consistent using a projector normally used for checking gear teeth and screw threads.

 

Much admire your clock photos and the excellent finish of your work – Regards – Pat

[Sam StonesParticipant @samstones42903]

Hi Pat,

 

Your comments about the springs in moving-coil meters are most interesting. I too, found that the end `finishes’ were important in getting my springs to work properly.

 

Although there is some angular variation with my clock’s balance wheel, I estimate that while the clock is ticking away, the total angular displacement is as much as 450 degrees of arc.

 

I suspect that variations in the angle of swing, relate to things like the fusee geometry, my rather crude gears, maybe the bi-metallic aspects of the balance wheel, and dare I say it – the condition of the main spring. I’m now concentrating on building a suitable case with a fabricated glass cover.

 

Also, thank you for your compliments.

 

Best regards,

 

Sam

[Sam StonesParticipant @samstones42903]

In getting close to completing each step of my skeleton clock, I believe that I owe several of you gentlemen a thank you and at least show my final method for making the balance spring. I must preface my notes by reviewing a few issues, and to intersperse acknowledgments for the ideas of others who helped me to reach what I believe is a viable solution.

Background

I have already mentioned in previous discussions that the helical spring in my John Stevens skeleton clock was originally intended to be a rectangular cross-section from wire 0.020″ x 0.005″ (I will stay in Imperial units for this exercise). It can be appreciated that a spring wound from wire with a rectangular cross-section offers lots of vertical stiffness, while remaining far less rigid in the direction it will bend in use. For a wide range of reasons, too numerous to list here, I elected to recalculate the stiffness in terms of round wire. This was a simple exercise to determine the equivalent stiffness (moment of inertia) in my CAD package. A wire 0.008″ in diameter was the result.

Where to get this size of wire?

Someone suggested guitar strings, and I was lucky enough to discover from a friend who owns a music shop, that this was the smallest string normally available over the counter. Such luck!

The finished sizes of the helical spring were to be 3/8″ OD and nine turns to produce a working length of about 3/8″. Had I still retained my Myford and other workshop machinery, I could have set the pitch accurately and wound the spring with the pitch built into the winding process. I would also have guided the wire onto the mandrel as was also recommended in various places and by the kind thoughts of other contributors. However, I had borrowed a lathe which was not very attractive in the screw-cutting department, and therefore elected to close-coil the wire. In other words, the wire would be touching itself on each successive rotation of the mandrel. I have also to say here, and as was explained to me some time ago, the wire is itself, caused to twist on its axis during the process of winding. I have no idea how this manifests itself, so I chose to ignore it other than to allow the wire to have the maximum amount of freedom as winding took place.

Winding tests showed that a 5/32″ steel mandrel would, when the wire was cut free, produce the requisite spring OD of 3/8″. Up until now, I had turned the power off to the lathe, and only turned the three-jaw chuck (backwards) by hand. Very tedious, but also fairly safe. Unlike running under power which is not recommended.

Controlling how the wire was held in place on the mandrel both during the winding stage, and before being released, had already been discussed elsewhere and amounted to applying pressure to the coils with a fixed piece of soft wood and running this with the lead-screw feed set to the spring pitch.

My efforts were abysmal.

I couldn’t control the coils which would wrap themselves together in an unglorified tangle. I was also drawing attention from SWAMBO, who had begun to notice how much time I was spending in the music shop, and how much housekeeping was going on emptying the music shop of guitar strings. So I needed another method of stopping the coils flying apart uncontrollably once I had made that necessary cut.

Method

Before explaining my technique, it is essential that you take great care to avoid accidents.

 

WINDING SPRINGS CAN CAUSE SERIOUS INJURY.

Using 0.008″ diameter guitar strings, which are about 39″ long, I ran a weighted nylon thread over a pulley for more than this length so that the guitar string had plenty of freedom to twist on its axis should that be taking place. My weight was a convenient drill chuck off the lathe, and weighed about 1/4 lb. The next tricky bit was threading the guitar string through a tiny hole drilled across the mandrel, sharp edges removed, and then rotating the lathe chuck until the end of the wire was caught and secure. The position of this hole in earlier attempts (with the hole drilled into the adjacent larger diameter of the mandrel) had, I believe, introduced some addition twisting into the wire as the wire slid briefly down onto the working diameter of the mandrel. The nylon thread (with weight attached), and the wire are suitably connected, and the winding process can begin. I also took great care to avoid kinking the wire in any way. Clearly, this would affect the desired outcome.

 

While I am certainly not recommending driving the chuck under power, I was running out of time, patience, guitar strings, and the need to avoid getting cramp in my old hands. I calculated that the winding time under power would be about 15 seconds, so I set the lathe in reverse (it has a bolt-on chuck so would not unscrew), and standing well clear, I turned on the power. It worked like a charm.

But I still had to stop the coils from spinning off the mandrel. It was then that I hit on the rather ludicrous idea of gluing the wire to the mandrel. Having noted on many an occasion that clock and watch makers use shellac as a glue, I pasted some of my own concoction over the coils, hoping that I could later soak the glue and the wire in meths and trusting that the coils would uncoil themselves slowly and under control.

It failed!

The shellac had not f

[Richard ParsonsParticipant @richardparsons61721]

Sam You are trying to wind a coil spring from a guitar string. This guitar string has been tensioned, hardened and tempered to set it into its shape –straight. To make it into a coil spring you have to do one of few things.

The first possibility is to undo all of the treatment and return it to its original soft state. To do this I would put the spring into an airtight metal (steel) container which is packed with (well riddled –to get rid of any combustible materials) ashes from a wood fire. (No you cannot use those ‘Ashes’ – we Poms have got them – for a time). I would then put the container into the back of a fire for a few days. Use the now softened wire to wind your spring. You will then have to harden and re-temper the finished product.

The second method and you may have to use this technique with the first method. Is to reduce the mandrel size so that you overcome the modulus of elasticity of the guitar spring and deform it so to give it a ‘permanent set’ to the radius you want. Your problem here is that a guitar spring is made to stay straight.

There is a third possibility which is to buy the finished product. I would H.S. Walsh (usual disclaimer). You can find them here. Have a look at the clock materials. You can Buy 72 of them for about 7.50 sterling and at 0.03 Kg the p&p to Oz will not be all that great.

Fourthly you cold machine up a sleeve which just slips over the former and the wire. Make a slot along its length. When you have wound your coil -keeping the tension on- slip the sleeve over the lot to hold everything in place. What you do next I have no idea!

Finally try google for ‘Spring Wire suppliers’, someone might send you a sample.

Good Luck

Dick

[Sam StonesParticipant @samstones42903]

Looks like my editing needs a shake-up.

I’ve just discovered that my last few paragraphs dropped off the end.

 

Please pick up from :-

 

It Failed!

 

The shellac had not found its way between the wire and the mandrel, or if it had, it had failed to set/dry. OK, I’ll use super-glue!

Have you ever bought 3ml tubes of super glue, and found that they contain less than half a ml? But that’s another story.

Super glue sets as it combines with moisture in the atmosphere. It also dissolves in acetone. You get my picture? I was down to my last guitar string, so my last attempt had to work. I painted a very thin layer of super glue onto the mandrel, and wound my remaining string as before. Then I painted an ample coating of super glue onto the coils, before heading off to my nearest (and cheapest) source of acetone. The Cheap Shop had nail-polish remover for a couple of dollars. Now came the witching hour as I cut the wire.

Zipp! The wire flew off the mandrel as before, but this time (it would appear), there was enough super glue remaining to hold the coils together rather than having them fly around. I dropped the promising result into the glass bottle of nail-polish remover, and waited for several hours, observing occasionally, that nothing was happening. Mumble grunt.

When I did finally fish the wire from the nail-polish remover, I could see under magnification, that there was still undissolved glue holding the coils in place. Gradually, I peeled off the glue to expose what I now consider to be a near perfect result. I was later informed by a kind gentleman that nail polish remover contains certain oils which could preclude the dissolving process, and that pure acetone might be the better option.

There, gentlemen is my method.

Best regards,

Sam

PS I’m well aware that there could be retained stresses within the spring, and that annealing is usually carried out, post winding. Frankly, my clock is running beautifully, which is what matters to me.

PPS

 

Thanks for your comments Dick. As you can see I’m satisfied with the way my clock is going. However, I feel sure that your ideas will be useful to future balance spring makers. 

Edited By Sam Stones on 01/07/2011 09:00:17

[Ian S CParticipant @iansc]

One way I’v used to anneal wire is to attach a wire to each end, and hook it up to a low voltage power supply, turn it on and let it heat up until red hot, turn off and let it cool, all done. Ian S C

[Richard ParsonsParticipant @richardparsons61721]

Ian that tip is very useful.

Thanks

Dick

[NJHParticipant @njh]

Hi Sam

 

Sorry to post to this thread but I can’t find the other.

Have you resolved the issue of a case for your masterpiece?

I have just received M&P’s latest catalogue and I see that they list hand blown Oval Glass Domes and wooden bases in various sizes from 140x90x300mm to 200x120x350mm.

Not cheap I’m afraid and shipping might be an issue I suppose however a traditional and worthy foil to your superb ( if at present inaccurate ) clock!

 

Best wishes

 

Norman

 

 

Edited By NJH on 01/07/2011 18:31:43

[Sam StonesParticipant @samstones42903]

Hello again, especially Dick, Ian, and Norman,

Thank you for all your ideas, I really appreciate getting your type of assistance.

Just a couple of points about the use of guitar strings, and also in making extra equipment. At the risk of repeating my earlier comments, my target is to finish the clock while I still have some dexterity left. I also consider my workshop to be a very temporary affair, and am reminded on occasions that the Hobbymat lathe is, after all, still on loan.

As some of my pictures show, the mechanism of a skeleton clock is intended to be fully visible. That’s the primary purpose of piercing the frames and wheels. In the case of John Stevens clock, the most obvious animation is the balance wheel and spring sitting inside the top `cage’. The nice thing about steel guitar strings, is that they are already polished. So if I can keep them in that condition, there will be less effort needed to bring them up to scratch. I would agree however, for those who like that sort of thing, that the spring could be a nice blue colour after tempering, but once again . . .

I like Ian’s idea of passing a low voltage current through the wire to soften it. I did notice that being rather fine, the wire burns immediately (like wire wool) if placed in a naked flame. I could also imagine that with care, the use of electrical current in this way, could be employed in both the rehardening and tempering after the wire has been wound to size. Holding it to shape would be quite a challenge however.

In my next comment, if not before, there is likely to be an element of `egg-sucking’ for grandmas. However, I’m inclined to believe that winding the wire around a 4mm diameter mandrel to get a finished diameter of about 8mm, does actually subject a percentage of the steel section to stresses above the elastic limit. How much of this will be in tension (or compression), I could not imagine. Clearly, there would also be a certain % of the section which does not get stressed beyond the yield point, or the spring would come off a 4mm mandrel at 4mm without any `snap-back’.

Machinery’s Handbook offers a table for Arbor Diameters for Springs Made from Music Wire and although it doesn’t actually mention the OD I needed, by extrapolation and my own tests, I seem to be on the right track at 4mm.

In terms of `annealing’ (I have difficulty with the definition of annealing), early tests of heating previously wound coils to about 200 deg C showed very little relaxation, and all the wire that I have wound since remains very close to what I wanted without this treatment.

Finally, and switching to Norman’s comments about the case (thank you Norman), and where to buy them, I have elected to follow John Parslow’s approach. Refer ME p202 15 August 2008. It concludes John’s article called “15-day skeleton timepiece”.

With the help of a friend with some good woodworking machinery, I now have a pine base suitably stepped, together with some pieces of Tasmanian oak beading to trim the surround. The ends of the beading have been mitred which is a task I have never enjoyed via the hand-sawing method.

I’m currently waiting for some shellac to dissolve and before I glue I will begin to apply this to the oak in multiple coats alternating with a rub-down with fine sand paper. I trust that PVA will hold everything together. The centre area of the base (inside the glass) will be covered in a dark blue material, the sort of cloth that is turned into tracksuits and the like. There’s a glass supplier down the road who has made fish tanks and display cases, so I’ll be talking to him next week. Alternatively, I’ll get him to cut the five pieces of glass, and glue them in place with clear silicone. Depending upon how the silicone runs between the glass, I imagine knifing off the excess to leave a very clean joint.

I reckon the French polish will be ready by now.

Regards to all,

Sam

Edited By Sam Stones on 02/07/2011 02:06:00

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again ,

 

When wire is bent to a tight radius around a mandrel the inner and outer regions of the wire are at yield stress . Tensile on the outside and compressive on the inside . The depth of these yield stress regions depends on the geometry of the setup and the material properties . The depth of yield stress regions outer and inner are not generally the same and the central region of the wire is stressed but well below yield .

 

When bending is finished but the wire is still constrained to be tight on the mandrel the inner and outer zones just sit there at yield stress or just below . The interesting thing happens when the wire is let free – the trapped stresses get released and the only way this can happen (apart from by heat treatment&nbsp is for the matching strains in the wire to release as well – ie the wire unwinds .

 

The stresses don’t nescessarily drop to zero everywhere because the stress distribution in a tightly bent wire or bar is very non linear and there is usually some stress permanently trapped .

 

A spring with any trapped tensile stress anywhere in the surface layers will have serious fatigue life and stability problems and springs for heavily loaded , critical aplications are always heat treated to reduce these tensile stresses to an acceptable level .

 

An ideal spring has a low level of trapped compressive stress in all the surface layers , inner and outer . This does not happen naturally so very high quality springs are sometimes shot peened or machine hammered to induce such a compressive layer .

 

A part of spring design almost always overlooked is the end connections – what happens there is very complex indeed and proper consideration of this area is important in designing springs especially for instrumentation where a very linear and ‘dead beat’ characteristic is required .

 

I’ve never looked into this in detail this but it seems possible that the ideal material for making small high accuracy springs is Nickel Chromium memory wire . Put a large radius initial curvature in the wire , lock it in , wind spring in the normal way then unlock – whereon the spring should neatly tighten up on the mandrel . Nickel Chrome wire is in any case a superb spring material and available in a large range of sizes .

 

Edited By MICHAEL WILLIAMS on 02/07/2011 10:41:53

Edited By MICHAEL WILLIAMS on 02/07/2011 10:47:07

[Sam StonesParticipant @samstones42903]

As always, Michael, your descriptions are explicit and promote even more thought.

Upon reading your latest posting, I’m drawn deeper into issues about stress distribution, stress relief, Poisson’s ratio, and the like. As for his ratio, it only really gelled in my mind while observing the movement of expanded lead mesh as used in accumulators (lead/acid batteries). However, that was a two-dimensional representation, whereas Poisson’s ratio more often deals in three dimensions.

I’m also left wondering about the surface stress, and the possibility of fatigue failure. I have only come across shot peening (academically) as a process applied to helicopter blades. As for this tiny spring of mine at 0.2mm diameter, I can understand that if the surface is in compression, it will contribute less to the spring’s performance, but is also less likely to facture in use. Since peening would have to be down to a micro scale, the only option (should I proceed) would be heat treatment. All I would be comfortable with would be to stick the spring in the kitchen mini-oven for an hour or two, but at what temperature?

Instead, I’ll take a chance and trust that the spring in the clock will outlive me. There’ll be less embarrassment that way round.

I also take your point about preparing the end connections. Not that I’ll be able to do much more then carefully curl the ends into line with the top (balance-wheel stud), and the bottom (balance-wheel collet) anchor points. This has led me to make a cylindrical template, such that one end was turned down a fraction to lineup with the stud hole, and the other end to match the hole in the collet.

Finally, you almost brought tears to my eyes when you mentioned nickel chrome. Not the wire so much as it being a favourite steel for plastics moulds, the business I started in as a raw apprentice.

 

Best regards,

 

Sam

[Author]

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